1Kernel driver pc87427 2===================== 3 4Supported chips: 5 6 * National Semiconductor PC87427 7 8 Prefix: 'pc87427' 9 10 Addresses scanned: none, address read from Super I/O config space 11 12 Datasheet: No longer available 13 14Author: Jean Delvare <jdelvare@suse.de> 15 16Thanks to Amir Habibi at Candelis for setting up a test system, and to 17Michael Kress for testing several iterations of this driver. 18 19 20Description 21----------- 22 23The National Semiconductor Super I/O chip includes complete hardware 24monitoring capabilities. It can monitor up to 18 voltages, 8 fans and 256 temperature sensors. Only the fans and temperatures are supported at 26the moment, voltages aren't. 27 28This chip also has fan controlling features (up to 4 PWM outputs), 29which are partly supported by this driver. 30 31The driver assumes that no more than one chip is present, which seems 32reasonable. 33 34 35Fan Monitoring 36-------------- 37 38Fan rotation speeds are reported as 14-bit values from a gated clock 39signal. Speeds down to 83 RPM can be measured. 40 41An alarm is triggered if the rotation speed drops below a programmable 42limit. Another alarm is triggered if the speed is too low to be measured 43(including stalled or missing fan). 44 45 46Fan Speed Control 47----------------- 48 49Fan speed can be controlled by PWM outputs. There are 4 possible modes: 50always off, always on, manual and automatic. The latter isn't supported 51by the driver: you can only return to that mode if it was the original 52setting, and the configuration interface is missing. 53 54 55Temperature Monitoring 56---------------------- 57 58The PC87427 relies on external sensors (following the SensorPath 59standard), so the resolution and range depend on the type of sensor 60connected. The integer part can be 8-bit or 9-bit, and can be signed or 61not. I couldn't find a way to figure out the external sensor data 62temperature format, so user-space adjustment (typically by a factor 2) 63may be required. 64